Inspector Harkins was shot and killed in the Main Post office in the Federal Building in Oklahoma City, Oklahoma. He was checking his post office box when a man walked up next to him and shot him in the back of the head. The suspect was upset at Inspector Harkins over the loss of two $20 money orders. After murdering Inspector Harkins the man stayed at the scene and turned himself in. He plead guilty to murder on a government reservation and was sentenced to life in prison. He died in prison on July 31, 1971, at the age of 96.